1. Field of the Invention
The present invention relates to a method for eliminating the reflective light disturbance of an optical disk affected by the light source of the optical disk drive, more particularly to a method used to adjust the illumination light source power parameter and adjust the reflective disturbance by dynamic feedback.
2. Description of the Prior Art
Optical disk drives are widely used in audio and video equipments in our daily life and computers information equipment as well, serving as the major equipment for playing the audio and video data and reading data from the computer. However, the components of the mechanism of the optical disk drive used for reading or writing data are illuminated laser components. The intensity of the light source determines the quality of reading and writing data; therefore the adjustment of the illuminating parameters of the laser components becomes extremely important.
The direct electric power relation value for the laser components"" illumination of a traditional optical disk drive is measured in milliwatt (mw), which uses the unit of power to represent its output brightness or output parameter, and the whole laser component""s illumination parameter is measured in milliwatt/ampere (MW/A) to represent its relative relation of output with respect to its input. Such value is generally considered as an electric voltage and such relation is briefly disclosed in FIG. 4; wherein the main electric power of the laser component A is an electric current I of a specific value, and the light source Pw emitted from the laser component A is exactly the above-mentioned output electric power value. In the reading or writing mode, the light source Pw passes through a set of lenses L1 and L2 and focuses at an optical disk B and makes the optical disk to generate a reflection. Such reflection Pxe2x80x2 is used by the light sensor (not shown in the figure) as a reference for reading data, some of the reflective light Pxe2x80x2 will reflect directly along the opposite direction of the original emission path back to the laser component A and it causes a noice to the power output of the output light source Pw. Such phenomenon is generally called reflection feedback. Therefore, the reflection feedback is listed as the key point for adjusting the illumination parameter in the reading and writing control system of an optical disk drive.
In FIG. 5, it shows a typical prior art of the automatic power control (APC) for the light source of a writable optical disk drive. Such system is used to describe the effect of the reflection feedback phenomenon, wherein the FPDO input value represents the power control parameter, elementary amplifiers R1 and R2 respectively represent the signal amplified units for the reading and writing systems of such optical disk drive, the controller PI and PIxe2x80x2 respectively represent the control unit for the light source control signal for controlling the output signal of the reading and writing of the optical disk drive, and the control signals are Vr and Vw, and the sampled signals are S1 and S2 which represent the sampled values for the reading and writing signals respectively. The reflective light disturbance caused by the emitting end of the laser component A has a reflection feedback value which is represented by dV, and the power value of the light source Pw and the noise N1 are computed by a monitor MD through feedback as an input value FPDO. Therefore, the disclosure of the APC system of the traditional optical disk drive as shown in FIG. 5 clearly shows that the reflective light disturbance value dV has a bad influence to the system stability, and the industry generally does not have a good adjusting method for such reflective light disturbance value dV. The difficulty is that such reflective light disturbance value dV is not a constant, and it varies according to the intensity of the light source Pw, and the quality of the signal pick-up head (such as the light sensor) and the layout of the printed circuit board. It means that the reflective light disturbance value dV are not consistently the same, and cannot be adjusted by a unified reference value derived from experience. Furthermore, the adjustment of such reflective light disturbance value dV has to be carried out when there is an optical disk acting as the reflection source. If there is no optical disk in the drive, the traditional adjustment method makes use of the monitor MD for adjustment. But since the factor of the reflective light disturbance is hidden, therefore the result of the adjustment is usually obtained from experienced values. Once the optical disk drive products are produced for accommodating an optical disk for reading and writing, the disk drive cannot accurately compensate or eliminate the reflective light feedback phenomenon because of the different reflective light for different optical disks. The adjusted system does not completely fit the reading and writing operations for all optical disks therefore occasionally it may have jumping tracks and is unable to read or write data accurately.
Further, if we consider to insert the optical disks one by one into the disk drive and obtain the actual reflective light disturbance value dV by adjusting the monitor MD, the intensity before the adjustment for the light source Pw cannot be controlled, so that the light source Pw causes the improper gathering of energy to focus at a point on the optical disk due to output power, and result in damage similar to punch holes, and burn the surface of the optical disk. It consumes a great deal of adjusting materials and costs, which is not commercially useful for the industry and not economically efficient. Further, the final adjusted result does not necessarily comply with the reading and writing operations for all optical disks.
The primary objective of the present invention is to provide a method for adjusting the reflective light disturbance for an optical disk drive by obtaining the preliminary parameters when the optical disk is not inserted into the disk drive, and then obtaining the illumination parameter through the dynamic feedback before the writing operation with the insertion of the optical disk, and adjusting the illumination intensity and illumination parameter for the laser light source, so that the reading and writing operations will not be affected by the reflective light disturbance.
A further objective of the present invention is to provide a method for adjusting the reflective light disturbance for an optical disk drive by obtaining an accurate and stable feedback adjustment parameters, so that it accomplishes the stable value for the illumination parameter of the laser light source in order to facilitate the recording in the memory for use.
Another objective of the present invention is to provide a method for adjusting the reflective light disturbance for an optical disk drive that does not need to consume a great deal of optical disk adjustment, and save the adjustment time and cost, and the instant adjustment due to the environment at different time.